A stator vane that is a main constituent element of a stationary component provided inside a steam turbine is fixed to a casing that surrounds a cylinder of the steam turbine, through a partitioning plate.
Drain water droplets included in steam collide with the stationary component of the steam turbine, for example, the partitioning plate, at high speed during operation. Therefore, a phenomenon (erosion) in which the surface of the stationary component is shaved occurs, and may compromise the function as the stationary component if the phenomenon is neglected.
Further, if crack occurs on the surface of the stationary component due to erosion, the steam enters the crack to cause a phenomenon (corrosion) in which the stationary component is corroded.
Accordingly, maintenance and inspection work of periodically replacing the stationary component such as the partitioning plate is performed before failure occurs due to erosion and corrosion, but a burden of the work is large.
Accordingly, as disclosed in Patent Literature 1, erosion countermeasures in which a portion where erosion easily occurs is subjected to weld overlaying of stainless steel or is covered with Ni-based alloy through plasma splaying, have been proposed. This extends a period until replacement of the stationary component, which allows for reduction of the burden of the work.